Komatsu F30791, Shop Manual

Page: 52 / 298

3. When opening area of control valve is small (small movement of lever)
When engine is at high idling
. When the control lever is operated in small move-
ments, or when it is operated to the HOLD position
(in other words, when the area of opening of the
control valve becomes smaller), the difference be-
tween pump pressure P
P
and LS pressure P
LS
(in
other words, LS pressure D P
LS
) becomes larger.
. When this happens, the movement is the same as
for "1. When control valve is at HOLD position":
pump pressure P
P
pushes piston (6) to the left
( ), so servo piston (4) is moved to the right
( ) in the direction of the minimum swash plate
angle.
In other words, the LS set differential pressure of
the LS valve is taken as 16 bar (16 kg/cm
2
).
In the range from the neutral position of the control
valve to the small area of opening of the control
valve (fine control), in the area where LS differential
pressure D P
LS
is more than 16 bar (16 kg/cm
2
), the
pump swash plate angle moves in the minimum di-
rection. If the area of opening of the control valve is
further increased, and LS differential pressure
D P
LS
goes below 16 bar (16 kg/cm
2
), the pump
swash plate angle is moved in the maximum direc-
tion.
10-34
PC20R-8 PC27R-8
Control valve
To actuator
LS valve
b
d
RKP01281
4
P
P
M
G
H
G
L
P
LS
P
LS
c
e
G
H
6
P
P
G
L
6